The purpose of this program continues to be to advance our knowledge of gastric cancer etiology with a multidisciplinary team approach to 2 unique populations: the peasants of Narino, Colombia and the blacks of Louisiana. The former display some of the highest rates known; the latter display rates much lower than those of Narino, but more than double those of Louisiana whites. Follow-up of cohorts of Narino subjects will be completed and correlations of histologic, chemical and epidemiologic parameters made. The progression of the precancerous process will be monitored with studies of cell kinetics and expression of fetal antigens in the gastric epithelium. Oncogenes in the gastric mucosa with cancer precursor lesions will be investigated. In vivo nitrosation will be studied in the two populations. The possible significance in the precancerous process of bacterial colonization, especially by campylobacter organisms, will be explored. Previous findings pointing to the role of carotenoids, tocopherols and ascorbic acid deficiencies will be followed up utilizing recently available techniques of reverse HPLC. The role of salt in carcinogenesis will be further explored. The genetic influence on the precancerous process will continue to be investigated. The multidisciplinary findings will be integrated to refine and test an etiologic model of carcinogenesis which is specific for the stomach but may contribute to models for other organs.